After the geth attack, Arcelia took shelter at Zhu's Hope, having possibly scouted the Prothean Skyway. She spends most of her time talking with Fai Dan. Though she can give an idea of the tactical situation—at least one dropship at ExoGeni Headquarters and Geth Armatures on the Skyway—Arcelia remains very negative and hostile when Commander Shepard arrives, claiming the Commander's heroics do not impress her. If Shepard comments on the strange behaviour of the colonists at Zhu's Hope, Arcelia snaps that they are civilians, who were never trained to deal with the horrors of war.

Arcelia has been infected with Thorian spores and, like the other colonists, fights to defend the freighter when Shepard returns from ExoGeni Headquarters. She initially lies in wait at the colony entrance barricades along with some colonists and Hollis Blake.

If she survives the attack on the freighter, Arcelia apologises for her behaviour; she tried to fight against the Thorian's control, but any thought of her own was excruciating.